Certain compositions of pressure sensitive adhesives (“PSAs”) are known to possess the following properties: (1) aggressive and permanent tack, (2) adherence with no more than finger pressure, (3) sufficient ability to hold onto a substrate, and (4) sufficient cohesive strength to be removed cleanly from the substrate. Materials that have been found to function well as PSAs include polymers designed and formulated to exhibit the requisite viscoelastic properties resulting in a desired balance of tack, peel adhesion, and shear holding power. PSAs are characterized by being normally tacky at room temperature (e.g., 20° C.).
Microsphere adhesives have proven to be extremely useful for use in PSAs because they allow a PSA-bearing article to be repositionable, i.e., to be attached and re-attached to different surfaces multiple times. Thus, microsphere adhesives have been used in consumable products such as, but not limited to, repositionable notes, repositionable flags or index tabs, and repositionable easel pads. Important characteristics of microsphere PSAs include, e.g., cost, manufacturability, environmental impact, and, of course, the above-noted adhesive properties. Typically, such adhesives comprise a reaction product of (a) a polymerizable monomer derived from petroleum-based resources, e.g., C4 to C14 alkyl(meth)acrylate, optionally a comonomer; (b) an initiator; and (c) a stabilizer, wherein the reaction occurs in water to yield a microsphere adhesive. Illustrative examples of such adhesives are disclosed in U.S. Pat. No. 5,571,617 (Cooprider et al.) and U.S. Pat. No. 5,714,237 (Cooprider et al.). Typically such monomers have been derived from petroleum-based sources.
The need exists for new adhesive compositions, and other products, that are made from renewable raw materials.